Analysis of Wastewater Reveals the Spread of Diverse Extended-Spectrum β-Lactamase-Producing <i>E. coli</i> Strains in uMgungundlovu District, South Africa

• Main Authors: Siyabonga N. Gumede (Author), Akebe L. K. Abia (Author), Daniel G. Amoako (Author), Sabiha Y. Essack (Author)
• Format: Book
• Published: MDPI AG, 2021-07-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Wastewater treatment plants (WWTPs) are major reservoirs of antibiotic-resistant bacteria (ARB), favouring antibiotic resistance genes (ARGs) interchange among bacteria and they can provide valuable information on ARB circulating in a community. This study characterised extended-spectrum beta-lactamase (ESBL)-producing <i>Escherichia coli</i> from the influent and effluent of four WWTPs in uMgungundlovu District, KwaZulu-Natal, South Africa. <i>E. coli</i> was enumerated using the membrane filtration method and confirmed using the API 20E test and real-time polymerase chain reaction. ESBL-producers were phenotypically identified by their susceptibility to the third-generation cephalosporins using the disc diffusion and the double-disc synergy methods against cefotaxime (30 µg) with and without 10 µg clavulanic acid. Genotypic verification was by PCR of the TEM, SHV, and CTX-M genes. The clonality of isolates was assessed by ERIC-PCR. The highest <i>E. coli</i> count ranged between 1.1 × 10⁵ (influent) and 4.3 × 10³ CFU/mL (effluent). Eighty pure isolates were randomly selected, ten from the influent and effluent of each of the four WWTP. ESBLs were phenotypically confirmed in 49% (<i>n =</i> 39) of the isolates, of which 77% (<i>n =</i> 30) were genotypically confirmed. Seventy-three percent of the total isolates were multidrug-resistant (MDR). Only two isolates were susceptible to all antibiotics. Overall, resistance to first and second-generation cephalosporins was higher than to third and fourth generation cephalosporins. Also, 15% of the isolates were resistant to carbapenems. The CTX-M-type ESBL (67%; <i>n =</i> 20) was the most common ESBL antibiotic resistance gene (ARG) followed by TEM (57%; <i>n =</i> 17) and SHV-types (27%; <i>n =</i> 8). Also, a substantial number of isolates simultaneously carried all three ESBL genes. ERIC-PCR revealed a high diversity of isolates. The diversity of the isolates observed in the influent samples suggest the potential circulation of different ESBL-producing strains within the studied district, requiring a more comprehensive epidemiological study to prevent the spread of ESBL-producing bacteria within impoverished communities.

Item Description

10.3390/antibiotics10070860
2079-6382